Pumps are commonly used for directing cementitious material, such as of the grouting type, to the location of use of the material. The cementitious material is typically transported and injected under pressure by means of a progressing cavity-type pump comprised of a helical rotor rotating within an elongated, contoured stator which is internally lined with an elastomer. A relatively compact, closed chamber known as a suction housing is disposed between and connects the input end of the rotor/stator combination with a conventional drive arrangement incorporating a motor with a rotationally displaced drive shaft. The closed suction housing is adapted to receive the wet cementitious material such as under a hydrostatic head and deliver it to the input end of the rotor/stator combination in a manner which eliminates the possibility of foreign material entering the pump during the pumping process. Pumps used for these applications are known as “closed throat” type pumps, and are available from various manufacturers. Pumps of this type direct the cementitious material to the location of application which frequently affords only limited accessibility.
Referring to FIG. 1, there is shown a partially cutaway perspective view of a prior art rotor/stator pump 10 which the present invention provides various improvements over. The rotor/stator pump 10 is generally in the form of an elongated, hollow tube and includes an inlet/drive stage 14 and a pumping stage 17. The inlet/drive stage 14 and pumping stage 17 are connected to various mounting/support brackets 11a, 11b and 11c which provide stable positioning for the rotor/stator pump 10 and allow it to be connected such as by bolts to a support structure which is not shown in the figure for simplicity. The inlet/drive stage 14 is comprised of a bearing housing 15 and a suction housing 19 which in the arrangement shown in FIG. 1 is formed as a single cast piece preferably comprised of aluminum. Disposed within and extending from the bearing housing 15 is a drive shaft 18 which is connected to a source of rotary power which also is not shown in the figure for simplicity. Disposed about and engaging the drive shaft 18 within the bearing housing 15 is the combination of a thrust bearing 20 and a radial ball bearing 22 to facilitate rotational displacement of the drive shaft. Also disposed about and engaging the drive shaft 18 and located generally within the suction housing 19 is the combination of a packing gland 24, packing 26 and a lantern ring 28 which form a seal between the suction housing and inlet/drive stage 14. Other conventional components are disposed within bearing housing 15, but are not discussed herein as these components are well known to those skilled in the relevant arts.
Attached to the suction housing 19 is an apertured inlet flange, or collar, 16 through which a wet cementitious material is deposited into the suction housing for introduction into a stator frame, or transport tube, 12. Cementitious material introduced into the suction housing 19 via inlet flange 16 typically flows under the influence of a hydrostatic head arising from the weight of the cementitious material. Drive shaft 18 is connected to an inner end hub of a rotor 32 within the suction housing 19 by means of a connecting rod 30. Opposed ends of the connecting rod 30 are pivotally coupled to the drive shaft 18 and the inner end hub of rotor 32 in a pivoting manner which allows the rotor hub to follow an elliptical path as it is rotated by the drive shaft 18. Connecting rod 30 thus imparts rotation to rotor 32, while allowing the rotor hub to follow an elliptical path above the axis of rotation. As rotor 32 is rotationally displaced, cementitious material is drawn out of the suction housing 19 and into the space between the rotor 32 and stator 34 and is displaced along the rotor/stator combination for discharge through an aperture 36 in the distal end 12a of the stator frame 12. A bolt 23 disposed in a lower portion of the suction housing 18, when removed, allows for discharge during cleaning of residue remaining within the rotor/stator pump 10 following use. Cleaning of the rotor/stator pump 10 after each use is essential for continued pump operation because of the cementitious composition of the material introduced into and displaced by the pump, but is very difficult to carry out in this prior art pump.
These types of pumps suffer from three basic recurrent problems. The problems arise from the limited access afforded by the pump's closed suction housing. First, pumps of this type are difficult to clean and maintain, as well as to disassemble for inspection or repair. For example, when the rotor is turning, its hub describes an elliptical path. Thus, a connection between the rotor's hub and an input drive shaft requires that this type of motion be accommodated. In the standard pump design, this is accomplished by means of a connecting rod disposed within a tubular drive shaft, one end of which is pinned to an end of the tubular drive shaft, while a second opposed end of the connecting rod is pinned to an end of the rotor hub. The connecting rod imparts rotation to the rotor, while also describing the elliptical path of the rotor hub. The standard design leaves the end of the drive shaft open and exposed to the product being pumped. This allows some of the product deposited in the suction housing to enter an end of the drive shaft. Because the product is a cementitious material, it often forms a solid mass within the drive shaft. This renders the connecting rod immobile resulting in excessive stator wear, and makes disassembly of the pump for inspection and/or maintenance difficult, if not impossible. This unfortunate situation also invariably results in reduced pump operating lifetime.
The present invention addresses the aforementioned limitations of the prior art by providing an improved suction housing for a rotor/stator pump used with cementitious materials which is easily disassembled to facilitate cleaning, inspection and repair of the pump. This invention also contemplates additional improvements which increase the reliability and prolong the operating lifetime of these types of pumps.